cc65/libsrc/geos-cbm/joy/geos-stdjoy.s

;
; Standard joystick driver for the C64. May be used multiple times when linked
; to the statically application.
;
; Ullrich von Bassewitz, 2002-12-20
;

	    .include "zeropage.inc"
	    .include "joy-kernel.inc"
	    .include "joy-error.inc"
	    .include "geossym.inc"

	    .macpack generic

; ------------------------------------------------------------------------
; Header. Includes jump table

.segment	"JUMPTABLE"
					     
; Driver signature

	.byte $6A, $6F, $79	; "joy"
	.byte JOY_API_VERSION	; Driver API version number

; Button state masks (8 values)

	.byte $01		; JOY_UP
	.byte $02		; JOY_DOWN
	.byte $04		; JOY_LEFT
	.byte $08		; JOY_RIGHT
	.byte $10		; JOY_FIRE
	.byte $00		; Future expansion
	.byte $00		; Future expansion
	.byte $00		; Future expansion

; Jump table.

	.word INSTALL
	.word UNINSTALL
	.word COUNT
	.word READ

; ------------------------------------------------------------------------
; Constants

JOY_COUNT	= 2		; Number of joysticks we support

; ------------------------------------------------------------------------
; Data.

.code

; ------------------------------------------------------------------------
; INSTALL routine. Is called after the driver is loaded into memory. If
; possible, check if the hardware is present and determine the amount of
; memory available.
; Must return an JOY_ERR_xx code in a/x.
;

INSTALL:
	lda #<JOY_ERR_OK
	ldx #>JOY_ERR_OK
;	rts			; Run into UNINSTALL instead

; ------------------------------------------------------------------------
; UNINSTALL routine. Is called before the driver is removed from memory.
; Can do cleanup or whatever. Must not return anything.
;

UNINSTALL:
	rts

; ------------------------------------------------------------------------
; COUNT: Return the total number of available joysticks in a/x.
;

COUNT:
	lda #<JOY_COUNT
	ldx #>JOY_COUNT
	rts

; ------------------------------------------------------------------------
; READ: Read a particular joystick passed in A.
;

READ:
	tax
	php
	sei			; disable IRQ
	lda $01
	pha
	lda #$35
	sta $01			; enable I/O

	txa	 		; Joystick number into X
	bne joy2

; Read joystick 1

joy1:
	lda #$7F
	sta cia1base
	lda cia1base+1
back:	tay
	pla
	sta $01
	plp
	tya
	and #$1F
	eor #$1F
	rts

; Read joystick 2

joy2:	ldx #0
	lda #$E0
	ldy #$FF
	sta cia1base+2
	lda cia1base+1
	sty cia1base+2
	jmp back